A third of the world's population is carrying tuberculosis, and the disease could become incurable if governments fail to act, the World Health Organisation (WHO) has warned. Lack of funding for public health programmes, the sale of inaccurate blood tests and the misuse of drugs, particularly in the private health sector, are hampering the fight against the disease and leading to drug resistance, says the organisation.
Extreme drug-resistant strains of TB have now been found in 70 countries, and doctors in India reported four patients this year who did not respond to any drugs at all. Doctors in Iran and Italy have also found patients who are apparently resistant to all drugs. Mario Raviglione, director of the WHO's Stop TB campaign, said: "What we are seeing worldwide is the emergence of strains of the bacillus causing tuberculosis that are resistant to most of the drugs we have available."
TB kills more people every year than any other infectious disease apart from HIV/Aids, and 95 per cent of deaths are in developing countries such as India, China, South Africa and Indonesia. Asia accounts for 60 per cent of new TB cases, and Sub-Saharan Africa has the most new cases per head of population. Two billion people are carriers of the TB bacillus. Infected people who are malnourished or have secondary illnesses are most likely to contract the disease, and 8.8 million contracted the illness in 2010. TB is the biggest killer of those with HIV, accounting for a quarter of HIV deaths.
The rate of TB deaths had declined dramatically – by 40 per cent between 1990 and 2000 – after a worldwide health campaign, which was particularly successful in China. But the emergence of drug-resistant strains threatens to halt progress and jeopardises the WHO's goal of eradicating the disease as a public health problem by 2050.
Drug resistance is growing because doctors are failing to prescribe the right number of drugs or because patients fail to finish the course of antibiotics. In some cases public clinics run out of stock, but increasingly, according to Dr Raviglione, private sector practitioners are to blame. In India, which has the highest prevalence of TB in the world, 50-70 per cent of patients go to private doctors when they start coughing. He said: "They don't want to queue in public clinics that are overwhelmed and congested. But the problem with private practitioners is you don't know who you are meeting and sometimes these people are just incompetent."
Instead of prescribing the four-drug, six-month regime recommended by the WHO, private clinics prescribe either too many drugs, "which is a waste of money and increases toxicity", or too few, which, Dr Raviglione said, increases drug resistance: "When someone has TB, you have billions of bacteria, and there is the possibility that one in 10 million or one in a 100 million is naturally resistant. If you expose this population of bacilli to one single drug, you kill the 999,999, but you don't kill that one that is resistant," which keeps growing.
When a doctor "undershoots" by prescribing too few drugs, not only does resistance grow, but the patient relapses and goes on spreading TB in the community. Professor Sarman Singh, a microbiologist at the All India Institute of Medical Sciences, said: "Many doctors will not adhere to the correct regime of TB treatment. Often TB is not diagnosed: they just suspect it. They give two tuberculosis drugs, and say come back in four weeks; that is very common."
A study of 100 Mumbai private doctors found that they prescribed 80 different drug regimes, instead of following WHO standards. But Professor Singh said that Indians who can afford to stay away from public hospitals will do so: "Every government hospital in India is overcrowded: they don't have chairs or sofas to sit on; they don't have air conditioning. Private practices have fewer crowds and there is no waiting period."
The sale of blood tests by private companies, a highly lucrative business, is also a problem, according to the WHO. Dr Raviglione said: "These serological blood tests can give you false positives and false negatives of up to 50 per cent, so you have a one in two chance that your test result will be wrong. These are done in the private sector, not public clinics, because they are not recommended by the WHO. So private physicians charge you $20 for a test which is useless."
The tests are made mainly by Western companies, but are sold to developing countries. The WHO called for these tests to be withdrawn more than six months ago, and the Indian government recently recommended a ban, but this is only effective in the public health sector; the tests are still being used by private clinics.
In the UK, TB cases reached a 30-year high in 2009, with 8,917 people contracting the disease. Although the number of cases fell slightly to 8,483 in 2010, the Health Protection Agency said control measures in Britain should be strengthened. More than 70 per cent of those contracting TB in Britain were not born in the UK; over half came from South Asia and a quarter from Sub-Saharan Africa.
South Africa has the third highest incidence of tuberculosis in the world. Thabo Mwale, who contracted the disease in 1994 and now lives with just one lung, set up a foundation to raise awareness of TB in South Africa. The biggest challenge, he says, is getting patients to visit clinics regularly to pick up their medication, particularly in rural areas. His foundation's volunteers take part in a government scheme to deliver drugs to patients at home or at work.
Sub-Saharan African countries and poorer Asian countries, such as Cambodia and Burma, rely on international donors for about half the resources to fight TB. Even middle-income countries such as China and Brazil, whose governments fund 95 per cent of TB prevention, need foreign donors to pay for medicines for patients who are resistant to multiple drugs.
Drug resistance has increased the cost of combating TB worldwide because additional, more expensive, medicines are needed. But international aid has dried up. The Global Fund, the international public-private scheme to combat TB, malaria and Aids, recently announced it could not fund any new projects until 2014 because governments have failed to pledge enough new money.